【摘要】 本文讨论了具有一个高阶奇点和两个零特征根的一类２ｎ＋１次系统，证明了这类系统可以存在两个ｎ阶细焦点，给出了极限环存在性和不存在性的条件，并证明了无穷远分界线环的存在性更多还原

【Abstract】 In this paper, we study a class of polynomial systems of degree 2n+1 on the plane with a higher order singular point and two zero eigenvalues and show that such a system may have two n th order fine focus. We also give the condition of existence or non existence of limit cycle, and prove the existence of the separatrix cycle at infinity.更多还原